The fifth spot? It could be filled by anyone from Vicente Padilla to Aaron Cook to Carlos Silva to Alfredo Aceves.
Do the Red Sox have enough pitching to compete in the American League East?
"I think we have more questions right now than Tampa Bay and New York, for example," said general manager Ben Cherington. "There's probably less competition for the rotation on those two teams. The Yankees made some moves to strengthen their rotation. Tampa Bay has had a strong rotation. Ultimately, the answer will be written on the field."
Even though he doesn't necessarily know who all the quality innings will come from, Cherington is confident he's assembled enough depth to enable some people to step up.
"Well, we've done a lot of math on that, trying to add it up," Cherington said. "It'd be nice, I suppose, to have five perfectly healthy guys that you knew for sure would give you 200 innings every year. I'm not sure we've ever had that, and this year's no different. As I said, we feel really good about the front of the rotation. We feel like we have a collection of guys that can win jobs and help us and fill spots.
"We feel confident that both Bard and Aceves are capable of doing it. That's not to say they'll both definitely be in the rotation, but they're both capable and they'll be coming to Spring Training as starters. We've got other options, and we'll keep our eyes open as we get closer to Spring Training or even into Spring Training if there are ways to strengthen the rotation."
There's always the chance Cherington could make another move that would free up enough payroll to bring in another proven starter -- like a Roy Oswalt. But at this stage, it doesn't seem like there will be any big changes before pitchers and catchers report to camp on Feb. 19.
"If Spring Training were to start tomorrow, we'd feel good about where we are and [we'd be] ready to put the team together," said Cherington. "We think we have a lot of options to fill our pitching staff. There will be competition in camp, obviously, both in the rotation and in the bullpen. We think we have some options.
"We had some internal options; we've added to those. We feel we're going to have enough depth on the position player side to figure out whatever we need to do there and perhaps protect against [Carl] Crawford not quite being ready on Opening Day. We'll see on that note. That said, Spring Training doesn't start tomorrow. We have our eyes open. If there's ways to improve the team between now and Feb. 19, we'll do that -- or after the 19th. We feel pretty good about where we are."
The best teams are not always the clubs that look the best on paper in January of February. Just look at the 2011 Red Sox, who went into last season looking like world beaters and missed the postseason altogether.
"There have been very recent examples of teams that looked like they were going to be struggling for depth at this point in the offseason, and [they] found some ways to put it together and did a good job buying low on some guys, and they figured it out," Cherington said. "Certainly, the personnel is a huge part of it. The names on the roster and the pedigree and all that is critical.
"I think the element that doesn't get talked about as much is the infrastructure ... [and] what we're doing to help our guys once they're out there, before they're out there. To help them get out there and help them succeed when they are out there, so our coaching staff is going to be challenged this spring in ways they haven't been in some recent years.
"Whenever there's competition and uncertainty, the coaches have more of a challenge, and we know they're up for that challenge. And again, like I said, we'll keep our eyes open if there's ways to protect the team more between now and not just Spring Training, but even Opening Day."